Second, Christians need the gospel to prevent the ever-present threat of legalism. Briefly, legalism arises in three ways: when we obey for the sake of conscience laws that are not expressly set down in Scripture, when we obey laws for conscience’s sake that belong in the old covenant but not in the new, and when obedience to God’s law is viewed as a means of our justification. When, for example, the gentile Galatian Christians were being hoodwinked by the claim that circumcision was necessary, Paul wastes no time to exclaim:
O foolish Galatians! Who has bewitched you? It was before your eyes that Jesus Christ was publicly portrayed as crucified. Let me ask you only this: Did you receive the Spirit by works of the law or by hearing with faith? Are you so foolish? Having begun by the Spirit, are you now being perfected by the flesh? Did you suffer so many things in vain—if indeed it was in vain? (Gal. 3:1–4)
Obedience to God’s law as the pathway to holiness is necessary. But if that obedience is motivated by anything other than gratitude for our salvation, it is the spirit of legalism. Such a spirit says that we are saved by Jesus Christ plus the evidence of our holiness.
Third, Christians need the gospel to deflate the scourge of pride. Augustine suggested that pride is the very essence of sin. J.I. Packer wrote:
Humility is the product of ongoing repentance as one decides against, turns from, and, by watching and praying, seeks to steer clear of pride in all its forms. And as the battle against pride in the heart is lifelong, so humility should become an ever more deeply seated attitude of living at the disposal of God and others—an attitude that veteran Christians should increasingly display. Real spiritual growth is always growth downward, so to speak, into profounder humility, which in healthy souls will become more and more apparent as they age.
The gospel is a reminder of why we need to be saved—our past, present, and future sins. Reminding Christians that they are, as Martin Luther put it, simul justus et peccator (justified and sinners still) will make the gospel all the sweeter on a daily basis.
Fourth, Christians need the gospel to enable a joy-filled life. Paul commanded the Philippians to “rejoice in the Lord always; again I will say, rejoice” (Phil. 4:4). Joy is a fruit of the Spirit (Gal. 5:22) and seems to be a central idea in Philippians. Writing from a prison cell, the Apostle Paul refused to allow circumstances to dictate the direction of his soul. The angel told the shepherds the meaning of the incarnation of Jesus: “Fear not, for behold, I bring you good news of great joy that will be for all the people” (Luke 2:10). The gospel brings daily joy as nothing else can.